One prior art oil industry process arrangement for producing transport fuel blendstocks, as previously conceived (and manifested in the design of many oil refineries worldwide), comprises a conventional refining flowscheme consisting of (separate and discrete) Crude Oil or Condensate Distillation, Saturates Gas Processing, Naphtha Pre-treatment, Continuous or Semi-regenerative Catalytic Reforming (CCR or PtR), and Kerosene Hydrotreating and Diesel Hydroprocessing plants. This process arrangement results in an operation where the benzene and aromatics contents of the resulting product motor gasoline pool can only be kept below the applicable specification maxima of 1% and 45% respectively at a low average pool RONC of around 92.5.
Supplementation of the gasoline pool by addition of high aromatics content (93-95 RONC) FCC (Fluid Catalytic Cracker) naphthas—even blended with high octane zero aromatics content (95-98 RONC) alkylates—does not materially alter the picture, as FCC naphthas also contain high quantities of benzene and other aromatics. Accordingly, approximately ½ to ⅔ of gasoline production of many existing oil refineries is low-octane 91R grade, unsuitable for modern motor vehicle engines (which require a minimum 95RONC), and which would in future have to be sold at lower export refinery gate “netback” prices into the lower product quality markets. Oil refineries also co-produce significant quantities of low value LPG, which can compete with surplus export by-product LPG from natural gas and LNG production.
Adding a Naphtha Splitter and Light Naphtha Isomerisation unit, the “traditional” refining industry naphtha isomerisation route to gasoline pool benzene and aromatics content reduction, achieves little, as it results in a process arrangement still barely able to satisfy even a 50/50% 95/91R gasoline grade pool demand, as gasoline benzene and aromatics content reach their respective specification maxima at an overall gasoline pool octane of around 93.5RONC.
Installation of a benzene saturation unit (“BenSat”) both consumes additional valuable hydrogen and simultaneously reduces pool octane by converting 100RONC benzene to 67RONC cyclohexane, which then has to be made up by a markedly higher severity CCR operation. The combined effect is to increase plant capital expenditure and decrease liquid yield, thus further reducing profitability. This effect is clearly demonstrated in the recent and impending closure of refineries worldwide with such antiquated processing schemes.
Typically in the oil refining and petrochemical manufacturing industry, process units are designed to manufacture products of a sufficiently high purity to meet a specified design quality standard. This usually results in the prior art process arrangements described being comprised of discrete process units, all with their own stand-alone primary reaction sections and secondary product purification facilities. These normally consist of fractionation columns and associated vessels, heat exchangers, pumps, valves and piping, and constitute significant capital investment, often comprising 50% or more of the Total Installed Cost (TIC) of the process unit.
The above description is not to be taken as an admission of the common general knowledge.